Posted
by
timothy
on Sunday October 10, 2010 @05:48PM
from the it's-lonely-in-space dept.

crimeandpunishment writes "If all goes according to plan, the only space sibling team will be hooking up in orbit. And not only are Scott and Mark Kelly brothers, they're identical twins. Scott took off Friday on a Russian Soyuz rocket to begin a five and a half month mission as the next commander of the International Space Station. Mark is the next commander of the space shuttle Endeavour, scheduled to lift off in February and hook up with the space station March 1st."

Seconds? I think you vastly overestimate the effect. The experiments that tested special relativity used atomic clocks and measured a few nanoseconds after travelling around the world several times in airliners. Even orbitals speeds for several weeks are going to make well under a millisecond's difference. The ISS travels at around 0.0026% of the speed of light. That's much too low for special relativity to have any effects that measurable with anything less sensitive than an atomic clock.

The effects of general relativity are even smaller - there's an experiment scheduled for 2013 that will compare an atomic clock taken to the ISS to one on the ground to test general relativity - the theory predicts a difference of one second over 10,000 years.

If I'm not mistaken (please correct me if I'm wrong here!) the furthest somebody has been from the Earth's surface and the fastest that anybody has ever traveled in absolute terms relative to the Earth was on Apollo 13. Not exactly a distinction that those astronauts were trying for, but it was a by product of the free return trajectory that they used to return back to the Earth. I don't know if these astronauts are the ones setting this record or not, but it is at least worth mentioning. Velocities of t

If I'm not mistaken (please correct me if I'm wrong here!) the furthest somebody has been from the Earth's surface and the fastest that anybody has ever traveled in absolute terms relative to the Earth was on Apollo 13. Not exactly a distinction that those astronauts were trying for, but it was a by product of the free return trajectory that they used to return back to the Earth. I don't know if these astronauts are the ones setting this record or not, but it is at least worth mentioning. Velocities of the

I wonder about those turtles on Zond 5... (a 1968 Soyuz mission which followed similar flight profile to Apollo 13; generally the first venture and safe return of macroscopic life beyond LEO...and it did perform more complex skip reentry profile, to limit g-forces, despite being normally capable of direct descend - so perhaps a bit faster)

And you know, if the speed of something can start to be measured by fractions of c - only then the ISS will have a trivial one. Or perhaps "order of magnitude more" would

Well... relativistic fountains of youth without entering orbit are out of the question. Cornell astronomer Dave Rothstein's "Ask" page [cornell.edu] cites pretty negligible gravity changes. Across the earth, he calculates within 0.01% of g for local geology (rock density and so on) differences.

Heights are more significant than that 0.01% change, but still won't reach a single percent: 0.2% * g for a 5 kilometer difference. Mount Everest [wikipedia.org] is 9km above sea level. If 9.81m/s/s is changed by even that single percent, we only

I screwed up my percent maths. The point is that 9.81 - (9.81 * 0.01) = 9.71m/s/s. Since nobody from Mount Everest ever reports regular floating in their gravity observations, gravity must be pretty mundane, so age won't have noticeable differences yet:)

Hey, you were the one too lazy to just ask "does relativity say that the elapsed time since their zygotes split from the embryo is now farther apart than it was before as they certainly have not been going exactly the same speed and subject to the same gravity their whole lives?"/now *thats* pedantic.

There may be more proof here that "It's not what you know, it's who you know!" than people realise... I mean, come on, how many of us young, fit, healthy, brainy people who'd be willing get this chance? What are the odds of them both being "the best of the best of the best, sir"?

Remember, "Disagree" is not a mod option! Remember, meta-moderation works! (or so they say...)

* They were married after they were both in the space program. They met as astronauts.

* NASA didn't find out that they were married until after the flight assignments were made and the two had been training together for some time. Given their choice, the NASA astronaut's office would have preferred to have kept them separated.

There may be more proof here that "It's not what you know, it's who you know!" than people realise... I mean, come on, how many of us young, fit, healthy, brainy people who'd be willing get this chance? What are the odds of them both being "the best of the best of the best, sir"?

Yeah, because if an individual has the right combination of nature and nurture to make him suitable to be an astronaut, what are the odds that someone with the exact same nature and a comparable nurture would be as well?

...to the tune of both finding themselves in a very small group selected among many? Though it's slightly more twisted, I imagine; something along the lines of "ok, we want him (due to whatever dynamics present, also partly somewhat outside of the hoped for optimums)...but there's two of him."

Yeah, because if an individual has the right combination of nature and nurture to make him suitable to be an astronaut, what are the odds that someone with the exact same nature and a comparable nurture would be as well?

So that's why things ended not so well for RDA Corporation in Avatar. I guess the nurture part wasn't close enough.

Um, if they both have the same genes, had the same upbringing and experiences in life, etc., then there's a good chance that if one of them is the best at something the other will also be rather good at it.

Really? Here at Slashdot we have those who discount the accomplishment of others on nothing more than "they won life's lottery" - "they were connected"? Then we have the declaration of how a certain poster is obviously astronaut quality while trying to make it appear that he is claiming many of/. is.

Here, I will give you a hint, instead of trolling bbs message boards in his younger days, or hanging out at the mall (it was the 80s after all) he was probably busting his ass. Actually, reading his and his

We should, nay must!, send one of them off into space at speeds near that of light! If we do not, future generations will rightly chastise us for missing this once-every-fifty-year opportunity to confirm the Twins Paradox. Ladies and Gentlemen, we know our duty. Now let us act upon it as women and men of science and of action!

NASA better be careful! They may have swapped classes in Astronaut school, and now only one of them knows, say, how to land the Shuttle, while the other one knows, say, how to work the zero-gee toilet!

On the other hand, when confronting the unknown dangers of space, it is really nice to have spare parts so readily available... although convincing your twin to give up those spare parts is another matter.